ODUj/k or ODUflex can be used to transport or switch Ethernet flows over Optical Transport Network (OTN) as defined in ITU-T Recommendation G.7041/Y.1303 (04/11) “Generic Framing Procedure” and ITU-T Recommendation G.Sup43 (02/11) “Transport of IEEE 10 GBASE-R in optical transport networks (OTN),” the contents of each is incorporated by reference. G.Sup43 defines several techniques to map and carry client traffic in clauses 6.2 “GFP-F mapping of 10 GBASE-R (LAN PHY) payload only into OPU2,” 7.1 “Bit transparent mapping of 10 GBASE-R signal into OPU2e,” and 7.2 “Bit transparent mapping of 10 GBASE-R signal into OPU1e.” GSup43 clause 6.2 is the only available technique to carry Ethernet packet traffic inside an ODUflex container. ODUFlex is an efficient method of carrying packet flows which do not fully utilize the constant Ethernet bit rates such as 10 G, 40 G, 100 G, etc. These packet flows do not have a constant bit rate, and the ODUflex can be sized appropriately. Also, there are mechanisms to resize hitlessly ODUflex containers. ODUflex advantageously allows efficient transport of Ethernet traffic over OTN. In the G.Sup43 clause 6.2 mapping mode, the GFP payload includes Ethernet Media Access Control (MAC) frames, and framing and signaling are handled by the GFP protocol, such as through Client Management Frames (CMF).
GFP CMF frames are used for Ethernet framing and signaling. In the case of a failure, the CMF frames are sent periodically, at a minimum of 100 ms interval, to a far end. The far end can use the CMF frames to detect an alarm condition and take appropriate action. However, due to the defined interval for CMF frames, overall detection and backward signaling between a near end and the far end may accumulate long delays before ports are declared operationally down, e.g., in excess of 300 ms. This leads to poor traffic protection performance and loss of data.